Abstract

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Power-combining schemes involving planar grids of solid-state devices or passive elements quasi-optically coupled in free space are an efficient means of combining power that makes them ideal for millimeter/submillimeter-wave applications by eliminating waveguide sidewall losses and machining difficulties. Three quasi-optical components including grid frequency multipliers, microswitch beam-steering grids and evanescent-wave couplers are presented.

A terahertz grid frequency doubler using a 6x6 diode-grid periodically loaded with planar Schottky diodes has been developed. A peak output power of 330[...] was measured at 1.00 THz for 2.42-[...] 500-GHz input pulses with a peak power of 3.3 W.

The microswitch beam-steering grid has potential advantages over mechanical-scanning devices or active beam-steering reflectors based on diodegrids such as lower losses and simple control circuits at submillimeter wavelengths. Micromechanical electrostatically-controlled [...]-membrane switches have been fabricated on silicon wafers to provide binary reactance control. Simulations predict that a 4-bit controlled 10-layer microswitch beam-steering grid can have a phase-shift resolution of 22.5[...] over 360[...] with a maximum loss of 1.6 dB and a maximum phase error of 5[...] at 240 GHz.

The metal-mesh evanescent-wave couplers have been demonstrated to have wider bandwidths and larger modulations than Fabry-Perot couplers. The evanescent-wave coupling effect has been studied and used to increase the efficiency of an optically-controlled amplitude-modulator at 56.5 GHz.